1. Field of the Invention
The present invention relates to a dustproof construction for a slider unit, which is envisaged to close effectively any clearance between a track rail and a slider unit to thus prevent foreign materials such as dust and dirt, oil mist and so on from entering into the slider unit and also keep debris, metal cuttings, oil contamination and so on owing to the slider unit itself against escape outside the slider unit through there.
2. Description of the Prior Art
Referring first to FIGS. 18 and 19, there is shown an example of prior slider units conventionally used in various fields such as semiconductor manufacturing apparatus, machine tools, assembling apparatus, testing instruments and so on, which are needed to work in any clean room. The slider unit is primarily comprised of an elongated track rail 2 opened upwardly at 27 to provide an U-shaped traverse cross-section to make a recess 5, and a slider 2 fitting snugly in the recess 5 of the track rail 2 for sliding movement relatively to the track rail 2, a recirculating-ball screw shaft 4 mating with the slider 3, and a driving motor 4 to turn the recirculating-ball screw shaft 4. The recirculating-ball screw shaft 4 is supported for rotation on the track rail 2 at both of a first bearing member 11 installed in an lengthwise end near the driving motor 9 and a second bearing member 12 installed in the lengthwise opposite end of the track rail 2, which is fastened to any basement by means of suitable fastener means such as screws. The slider 3 is installed to move linearly along the track rail 2 through rolling elements. A bottom 6 and a pair of upright side walls 7 define in combination the upwardly opened recess 5 in the track rail 2. The side walls 7 are provided on their widthwise opposing inner surfaces with raceway grooves 8 that extend in parallel with each other lengthwise along the track rail while the sliding element 3 has raceway grooves confronting the raceway grooves 8 to define a load raceway between them. Rolling elements may run through the load raceway, thereby making the slider 3 move smoothly along the track rail 2.
The slider 3 has a pair of widthwise opposing upright flanges 13, which are to mount an object such as a workpiece table on the slider. The flanges 13 are made with threaded holes 14 for fixture means such as bolts to hold any object thereto. A dustproof cover 15 is attached to the bearing members 11, 12 so as to shield the track rail 2 with the exception of sidewise clearances 33 where the flanges 13 are allowed to move back and forth through there. Thus, the dustproof cover 15 is arranged above all of the slider 3 and the recirculating-ball screw shaft 4, which constitute in combination a torque-to-thrust conversion system for the slider unit, thereby keeping dust and debris against entering into and also coming prom inside the track rail 2. A pair of the upright flanges 13, on which the object to be moved is loaded, should be formed so as to be unobstructed with the dustproof cover 15. To this end, the upright flanges 13 each extend widthwise outwardly of the slider 3 and then turn upwardly to thereby provide a substantially L-shape in front view. The slider 3 has a nut 17 made therein with an internal helical groove that will mate with an external helical groove provided around the recirculating-ball screw shaft 4. The combination of the screw shaft 4 with the nut 17 constitutes a torque-to-thrust conversion system in which the rotation of the screw shaft 4 results in driving linearly the nut 17 along the track rail 2. The lengthwise opposite bearing members 11, 12 are mounted on railheads 20 of the upright side walls 7, 7 of the track rail 2. The railheads 20 are finished in parallel with the raceway grooves a of the track rail 2.
Sensor rails 22 are disposed on sidewise outsides of the upright side walls 7 of the track rail 2, each to side wall. The sensor rails 22 are each provided with a limit sensor 23 at any preselected place to sense the associated flange 13, followed by issuing the detected signal to a controller through a lead wire 24 and a sensor connector 25. The driving motor 9 is energized depending on any control signal applied through a motor connector 28 to produce a torque transmitted to the recirculating-ball screw shaft 4 via a coupling 30. A fore-and-aft range over which the slider 3 is allowed to travel is defined with stoppers 31, 32 that are secured to the bearing member 11, 12, each to each bearing member.
In Japanese Patent Laid-Open No. 325070/1999 there is disclosed a sealing construction for the slider unit constructed as stated earlier, in which bellows-like sealing means are installed to keep foreign matter such as dust, debris and so on against entering into and coming from inside the slider unit through the sidewise clearances 33. The bellows-like sealing means are each composed of at least one sealing member expansible owing to its own elasticity, which is secured to anyone of the confronting lengthwise edges of the track rail 2 and the dustproof cover 15 to close the associated clearance 33. When the slider 3 travels along the track rail 2, the flanges 13 extending across the clearances 33 are allowed to move smoothly because the sealing members are easily subject to the elastic expansile and collapsed deformation and thus thrust aside by the action of the moving flanges 13.
Another example of the sealing constructions for the slider unit made as stated earlier is disclosed in Japanese Patent Laid-Open No. 27235/2001, in which expansible sealing members are arranged in gaps between the track rail 2 and the dustproof cover 15 in a manner allowing the flanges 13 to travel through the gaps on the sliding movement of the slider 3 along the track rail. Each expansible sealing member is composed of upper and lower sealing parts that are urged elastically against each other to close the associated gap. When the flange travels across the associated gap, the upper and lower sealing parts are shoved apart from each other at only a region closely neighboring the moving flange to allow it to travel between the sealing parts, with keeping a sliding contact with the opposite surfaces of the moving flange. At the residual regions before and after the moving flange, however, the upper and lower sealing parts are kept in abutment against each other due to their own elasticity. Moreover, the upper and lower sealing parts are made in an elongated configuration that is attached at one lengthwise side thereof to any one edge of the gap and abutted against the counterpart with their own elasticity. The lower sealing part is made greater in elastic force than the upper sealing part to compensate the influence of gravity.
With most prior slide units, any elongated slits or clearances 33 are left uncovered between the dustproof cover 15 and the track rail 2 to allow the flanges 13 for supporting thereon a workpiece table to travel back and forward integrally with the slider 3 along the clearances 33, with extending sidewise across the clearances 33. This means many conventional slider units should not be able to effectively prevent foreign materials such as dust and dirt, and so on from entering into the slider unit through the clearances 33 and also keep debris, metal cuttings, and so on owing to the slider unit itself against scattering all around through the clearances 33 in the clean room where the semiconductor manufacturing machines are installed. To cope with this, various ways constructed as stated earlier have been proposed to keep dust and debris against entering into and escape out of the dustproof cover through slits, clearances 33 and so on. Nevertheless, the major obstacles to all the sealing constructions in which the bellows-like expansible sealing members are installed to close the sidewise clearances 33 and in which the upper and lower expansible sealing parts are urged elastically against each other to close the clearances 33 are necessitating the sophisticated expansible sealing members that are very tough to form them and thus become high in their production cost. Moreover, another problem faced in the expansible sealing members as stated above is making sure of elasticity, with even superior sealing property.
The present invention, therefore, has as its primary object to overcome the problems as stated just above and to provide sealing means for a slider unit, which is provided with a sealing member simple in construction and also inexpensive in production cost. The major object of the present invention is to provide sealing means for a slider unit, in which sidewise wings of the slider are allowed to travel back and forward across sidewise clearances left open between a track rail and a dustproof cover at widthwise opposite sides of the slider unit, and especially to provide the improved sealing means wherein expansible cellular members are installed to close the sidewise clearances, but collapse to allow the sidewise wings to move across the clearances, thereby preventing foreign materials such as dust and dirt, oil mist and so on from entering into the slider unit and also keeping debris, metal cuttings, oil contamination and so on owing to the slider unit itself against escape outside the slider unit through there into a clean room where the semiconductor manufacturing machines are installed.
The present invention is concerned with a sealing means for a slider unit, comprising a track rail having a pair of lengthwise side walls opposing to each other widthwise of the tack rail, a slider movable on the track rail, and a cover arranged over the track rail in a manner spanning between the side walls, wherein sidewise clearances are left open between the cover and the side walls of the track rail, each to each side wall, in a manner extending lengthwise of the track rail, the slider is made integrally with wings extending sideward from sides of the slider, each to each side, across the clearances and terminating in flanges turned upward, and sealing members of flexible, porous substance are arranged in the clearances between the side walls of the track rail and the cover to close the clearances, each to each clearance, in such a way that the sealing members are each fastened to any one of the associated side wall and the cover and allowed to experience any deformation of expansion/collapse, with keeping sliding engagement with the associated wing that pushes its way out the sealing member when the slider travels along the track rail
In one aspect of the present invention there is disclosed a sealing means for a slider unit, in which the sealing member is formed conforming to a contour of the clearance. For instance, the sealing member is made in a configuration of substantially quadrilateral in traverse cross-section, which may experience any deformation of expansion/collapse at place where the wind of the slider travels there, with keeping substantially the initial quadrilateral. As an alternative, the sealing member is made in a traverse cross-section in which an area near a lengthwise surface to be fastened to any one of the side wall and the cover is made widthwise thick while a remaining area is reduced gradually in widthwise thickness towards an opposite surface, which will come into sliding engagement with the associated wing of the slider. With the modified sealing member stated just above, the deformation of expansion/collapse caused in the sealing member when the associated wing of the slider travels will occur substantially in only the area slim in width and further the deformation is kept against bulging out sideward beyond the width of the thick area. Thus, the modified sealing member is able to continue ensuring substantially its initial configuration in cross section even under any deformation of expansion/collapse and, therefore, will never interfere with any motion of other parts owing to the deformation of expansion/collapse.
In another aspect of the present invention, there is disclosed a sealing means for a slider unit, in which the sealing member has a spring element to intensify a restoring force of the sealing member after subjected to any deformation of expansion/collapse occurring due to travelling of the wing of the slider. The spring element is arranged in a way extending lengthwise along any side of the sealing member, which will come into sliding contact with the wing of the slider.
In another aspect of the present invention, there is disclosed a sealing means for a slider unit, in which the sealing member is made of foal rubber. Moreover the foam rubber to provide the sealing member is coated with a protective skin.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the sealing member has a fastener plate on a surface thereof to be secured to any one of the side wall and the cover.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the sealing member has a wear proof slideway belt lengthwise on a surface thereof coming into sliding engagement with the associated wing of the slider. Moreover, the wing of the slider also has a wear proof slideway belt on a surface thereof coming into sealing member.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the cover encloses a top surface of the sealing member to shield the sealing member. Moreover, the cover is comprised of a roof to shield the top surfaces of the sealing members, and widthwise opposing side panels hanging from the lengthwise edges of the roof into gaps between the sidewise outsides of the sealing members and the flanges of the slider.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the track rail includes a bottom integral with the side walls to be made in a trough opened upward.
In a further another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the slider is allowed to move back and forward with smoothness by virtue of rolling elements that run through load raceways defined between raceway grooves on widthwise opposite sides of the slider and raceway grooves on the sidewise opposing inside surfaces of the side walls.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the sealing member is comprised of upper and lower sealing halves laid one on top of another, the upper half being fastened to the cover while the lower half being secured on the side wall, and the wing of the slider is arranged to move back and forward between the upper and lower sealing halves.
In a further another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the track rail is composed of a guideway member made with raceway grooves confronting raceway grooves on the slider to define load raceways between them to allow rolling elements to run through there, and a base frame has the side walls to hold the guideway member.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which a pair of the guideway members are spaced sidewise apart from one another and secured lengthwise to the base frame, while the slider is arranged to fit over the guideway members.
In another aspect of the present invention there is disclosed a sealing means for a slider unit, in which the slider is comprised of a sliding part made with raceway grooves that cooperate with raceway grooves on the guideway member to define load raceways between them where rolling elements are allowed to run through there, and a carriage mounted on the sliding part and including the wings extending sideward and terminating in upward flanges.
With the sealing means constructed as stated earlier, the sealing members of foam rubber may effectively closed the sidewise clearances left open between the dustproof cover and the side walls of the track rail. Nevertheless, the sideward wings of the slider are allowed to travel back and forward with smoothness between the sealing members and either the side walls or the dustproof cover, with making sure of sealing effect on the clearances between the sealing members and either the side walls or the dustproof cover. The sealing member, as designed in a configuration conforming to the contour of the clearance, may be easily subjected to any deformation without substantial effort to push the sealing member aside when the associated wing of the slider travels across the clearance with thrusting its way out the sealing member. This is favorable for making sure of good sealing performance. According to the sealing construction of the present invention, there is no possibility that foreign materials such as dust and dirt, and so on either enter into or come from inside the slider unit through the clearances left open between the dustproof cover and the side walls of the track rail. Especially, debris, metal cuttings, and so on owing to the slider unit itself are kept against scattering all around through the clearances in the clean room, which will be thus maintained in any desired cleanliness. As the foam rubber for the sealing member is made in a simple quadrangular shape in traverse cross-section, rather than any sophisticated shape and structure that might introduce costly production requirements, the sealing member devised in the present invention can be much reduced in its production cost and also is easy to apply it to any clearance left open between the dustproof cover and the side wall.
The sealing member made in the quadrangular shape in cross section is allowed to simply collapse and/or expand with no need of substantial effort to push the sealing member aside at any place where the associated wing of the slider travels across the clearance, thus making sure of good sealing performance. Moreover, in the modified sealing member in which an area near a lengthwise surface to be fastened to any other member is made widthwise thick while a remaining area is made slim in widthwise thickness towards an opposite surface making any sliding engagement with the associated wing of the slider, only the slim area is allowed to expand and/or collapse with much smoothness when the wing of the slider pushes its way out the sealing member. In addition, as the slim area is certainly kept against bulging out sideward beyond the widthwise thickness of the thick area, the sealing member may be expansible and collapsible with keeping substantially its initial quadrilateral.
The spring element installed in the sealing member lengthwise along the side making any sliding contact with the wing of the slider is to intensify the sealing member in force to restore its initial shape after subjected to the deformation of expansion/collapse. Even if the foam rubber of the sealing member 1a were subjected to deterioration due to aging, for instance, even when the wing of the slider were actuated after stood idle for a long period moreover, any resilient force of the spring element would aid the sealing member to immediately restore its initial shape from the deformation of expansion/collapse, without leaving signs of the associated wing on the sealing member. Thus, it will be expected that the resilient force of the spring element works by improving the response of the sealing member to the expansion/collapse, thereby raising the close engagement of the sealing member to other surfaces to make sure of high sealing performance.
With the sealing means constructed as stated earlier, since the sealing member itself is made in a very simple configuration in traverse cross-section, for example made in either a quadrilateral or a trapezoid composed of thick and slim areas, and also formed conforming to the contour of the clearance, the sealing member may be fit simply in the clearance left open between the dustproof cover and the side wall of the track rail and less subject to any irregular deformation, thus realizing improvement in sealing performance, with even inexpensive in production cost. With the sealing means stated above, debris, metal cuttings, oil mist and so on owing to the slider unit itself are kept against scattering outside the slider unit in, especially, the clean room where the semiconductor manufacturing machines are installed, and moreover the occurrence of the debris owing to wear is made most reduced ever realized. Consequently the sealing means for slider units according to the present invention serves good sealing function and there is no occurrence of any obstacle in the clean room, which might be because the slider unit itself. Further, the sealing construction using the sealing member of porous substance such as foam rubber is effective to protect the slider unit against an invasion of foreign matter such as dust and dirt through the clearances in the slider unit.
The above and other related objects and features of the present invention will be more apparent to those skilled in the art from a reading of the following description of the disclosure found in the accompanying drawings and the novelty thereof pointed out in the appended claims.